1. Field of the Invention
The present invention relates to an optical modulator for modulating a light beam irradiated by a light source in accordance with image information, and an optical device and a projector having the optical modulator.
2. Description of Related Art
Conventionally, a projector having a light source, an optical device for modulating a light beam irradiated by the light source in accordance with image information and a projection optical system for enlarging and projecting the light beam modulated by the optical device has been known as an optical equipment using an optical device (see Japanese Patent Laid-Open Publication No. 2000-89364).
The optical device of the projector has three optical modulators for modulating color light in accordance with image information, and a color combining optical system for combining respective light beams modulated by the optical modulators to form an optical image.
The optical modulator has an optical modulator body having a pair of substrates sealing an electrooptic material such as liquid crystal therebetween and a holding frame for accommodating and holding the optical modulator body.
The pair of substrates of the optical modulator body includes a first substrate on which a data line, a scan line, a switching element, a picture electrode etc. for applying driving voltage to the electrooptic material are formed, and a second substrate on which a common electrode, a black mask, and a color filter as necessary are formed.
The holding frame has an accommodating portion for accommodating the optical modulator body, and a fixing plate for positioning the optical modulator body inside the accommodating portion. The optical modulator body is accommodated in the holding frame with one of the substrates facing to the side of the accommodating portion of the holding frame and, subsequently, the optical modulator body is pressed by the fixing plate from the side of the other substrate.
In such optical modulator, the data line and scan line formed on the first substrate and the black mask formed on the second substrate etc. absorbs the heat generated by irradiating the light beam from the light source, thereby raising the temperature of the first and the second substrates. Accordingly, the heat of the substrates has to be released.
The substrate disposed on the accommodating portion side contacts with the accommodating portion on a large area, the heat can be efficiently released by constructing the accommodating portion with a heat-conductive material such as metal.
However, heat of the substrate located on the side of the fixing plate cannot be efficiently released, because the fixing plate is constructed by a thin plate and therefore has small heat capacity and the fixing plate only partially contacts with the substrate to press and hold the substrate.
Though it is possible to thicken the fixing plate to increase the heat capacity of the fixing plate, such arrangement inevitably increases the thickness of the optical modulator and the size of the optical device provided with the optical modulator, so that size reduction cannot be achieved. Further, since the gap against an optical element disposed on the downstream of the optical modulator such as a polarization plate is enlarged, image quality such as color evenness and contrast may be deteriorated.